Towards zero energy buildings: retrofitting an existing recreational facility: A case study of a sauna facility on Styrsö

Examensarbete för masterexamen
Master's Thesis
Infrastructure and environmental engineering (MPIEE), MSc
Bwira, Bertil
Khalayli, Tarek
A resolution by the European Union adopted in 2010 designates that all new buildings in the EU must be classified as nearly-zero energy buildings (nZEB) by the end of 2020. A recent proposal by the Commission specifies that by 2030, all new buildings are to be zero-energy buildings (ZEB). A nZEB is defined as a building with a very high energy performance where the total net energy consumption is nearly zero, whereas a ZEB is defined as a building with a total net energy consumption equal to zero. The directive also includes that every member state in the EU has to present a renovation plan for the existing building stock to decrease their environmental impact and achieve the goals of the EU. Sweden has introduced a climate policy framework aiming to have net zero emissions by 2045 and is developing a long-term renovation strategy in line with the EU. This study investigates the energy reduction potential and the energy performance of a very energy-consuming building. The project focuses on a recreational facility on Styrsö in the southern archipelago of Gothenburg, Sweden. Moreover, the project aims to create awareness and convert the sauna facility at Styrsö Hafsbad into a nZEB using European and Swedish criteria and definitions, with the ultimate goal of achieving ZEB. In addition, a cost-benefit analysis was conducted to ensure that the proposed actions could be implemented economically. The existing sauna facility Styrsö Hafsbad was analyzed by means of a case study. Using thermal and electrical measurements, data will be partly gathered on-site. Furthermore, building measurements and layers will be recovered off-site using prior construction blueprints, while total water and energy use will be estimated using older receipts. A literature review was conducted to address the research questions by collecting and analyzing information acquired by keyword searches on selected databases, including Google Scholar, Mendeley, government agencies, and published theses. Understanding building energy balance, energy demands, energy-reduction strategies and measures, and other relevant terminologies are crucial for the literature review chapter. The building was simulated using the energy simulation software IDA-ICE. The results demonstrate that both nZEB and ZEB status are possible. The simulations showed that the change of ventilation system and installation of an air-to-air heat pump resulted in a total energy reduction of 71%, enough to achieve nZEB. The remaining reduction came from installing solar cells and changes in the building envelope, including lowering the temperature. A combination of the measures mentioned has to be applied to achieve ZEB. The initial strategy for achieving net-zero in the building is to reduce its primary areas of demand, with heat loss reduction measures having the most significant impact, followed by energy-efficient appliances and solar cells. Simulations demonstrated a slight reduction in energy usage when the roof was insulated, or the windows were replaced. Setting up a new air-to-air heat pump is more economical and prudent from a cost-benefit perspective. According to all economic performance approaches, it is a good metric. Additionally, ventilation systems are economically beneficial. On the other hand, alterations to the building envelope proved inefficient both econonomically and energy-performance-wise.
Climate-neutral building, energy footprint, energy renovation, NZEB, ZEB
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